This invention relates to automatic tool changers for rotary toolheads with cross-feed tool slides such as disclosed, for example, in co-pending U.S. Patent Application, Ser. No. 751,962, which was filed on Dec. 17, 1976, by Ervin J. Kielma, Frank J. Schalk and Kenneth J. Merkel, for a "Machine Tool With Counterposed Rotary Toolheads Carrying Cross-feed Tool Slides". Said copending patent application discloses two rotary toolheads each of which carries two cross-feed tool slides on which tools are mounted. But, the tools have to be mounted on the tool slides by hand, which is difficult with large tools and is time-consuming even with small tools. Accordingly, the principle object of this invention is to provide an automatic tool changer which is adapted to automatically change tools on a cross-feed tool slide which is mounted on a rotary toolhead. Other objects and advantages of the invention will be apparent from the detailed description herein.